Bottom Painting Aluminum Boats

[thill]

Here is something I've never faced before. I have an 18' Starcraft that is in great shape, but the previous owner bottom painted the boat. Today, I used a power washer, and blasted off the old loose layers of paint, and I want to re-paint. I've done lots of bottom paint, but never on an aluminum hull.

What paint to use? I've heard two schools of thought...

1. Apply 2 layers of epoxy barrier coat to the hull, and then use whatever bottom paint you want.
2. Use a special bottom paint made specifically for aluminum boats.

I can't tell what the previous owner did. That tough, dark stuff underneath kind of looks like barrier coat.

For you who have done this over a number of years, what have you done and what do you prefer?

Thanks

 

[airshot]

Where is your boat being moored ?? Trailered, salt water, fresh water ??? Makes a big difference !!

 

[thill]

In this case, it will probably live on the trailer. But it needs something, so it doesn't look like it's got leprosy. I just want to make sure I get it right.

From what I'm learning, Trilux 33 or Vivid should fit the bill. No copper, and they are hard epoxy paints, not alblative.

 

[LaqueRatt]

Here's a third school of thought. There is this stuff called aluminum paint. Available at True Value Hdw and I'm sure elsewhere. It looks a great deal like polished aluminum. It actually has aluminum particles in it. I spent two hours scraping a 14 footer, inside and out. Rubbed it down with paint thinner and went to town with a paint brush. It was far from perfect, but to see the defects you had to have your nose right up to it. Sold the boat, so can't say how well it held up, but I look at it this way. If it comes off, 5 mins with a paint brush will fix it.

 

[mbullen]

Lots of avenues there. If it's a fresh water boat living on a trailer, it doesn't even need to be bottom paint.
My only suggestion is to avoid anything with copper.

 

[Smokey101]

Get off ALL of the old paint, use a self etching primer. Spray the new paint and use hardner additive

 

[DaleH]

Or ... do it simple ...

Get off any of the loose paint, prep any bare spots with a white vinegar wash using an aggressive scrubbie pad, then rinse. Add suitable metal primer to bare spots when paint with Rust-Oleum enamel of your choice ...

A trailered boat bottom paint isn't rocket science, just as long as you don't use anything with copper as noted ...

 

[LaqueRatt]

I agree with Dale, except maybe on the vinegar. The paint I used said explicitly to prep using thinner. Went after it with a pile of shop rags and was amazed how clean it came out. I didn't even take soap and water to it, the thinner got it spotless.

 

[Ronbedard57]

Amen to Rustoleum top coat.

 

[Smokey101]

I agree with Dale, except maybe on the vinegar. The paint I used said explicitly to prep using thinner. Went after it with a pile of shop rags and was amazed how clean it came out. I didn't even take soap and water to it, the thinner got it spotless.

I agree, people think that vinegar is a cure all that is great for everything including losing weight, I call hogwash, but it does make a good weed killer.

 

[thill]

Some good thoughts here.

I don't feel like stripping down to metal and starting over. There is still bottom paint there.

I could put Rustoleum or aluminum paint over what is there, and it might look decent, but what if the ablative paint starts wearing? Not a good look.

I think it best if I just topcoat with a suitable bottom paint of the same color. Then the buyer can leave the boat in the water for the season, if desired, like the previous owner did.

Less work, more consistent results

 

[KMixson]

Some good thoughts here.

I don't feel like stripping down to metal and starting over. There is still bottom paint there.

If the old paint was scraped off during the previous years of use, you could paint over it. Now, if the old paint flaked off, you want to remove it. If it flaked off the new paint will come off as the old paint flakes off. You want the new paint to have a good foundation, whether it be old paint or bare hull. One other little tidbit of info, if you paint over the old paint, feather the edges of the old paint really good. You don't want to feel the edge under the new paint. That would create a spot that will me more likely to start chipping off while in use. The smoother, the better.